Tetrazole amphiphile inducing growth of conducting polymers hierarchical nanostructures and their electromagnetic absorption properties.

Conducting polymers (CPs) at nano scales endow materials with special optical, electrical, and magnetic properties. The crucial factor to construct and regulate the micro-structures of CPs is the inducing reagent, particular in its chemical structure, such active sites, self-assembling properties. In this paper, we design and synthesize an amphiphile bearing tetrazole moiety on its skeleton, and use this amphiphile as an inducing reagent to prepare and regulate the micro-structures of a series of CPs including polypyrrole, polyaniline, poly(3,4-ethylenedioxythiophene) and poly(p-phenylenediamine). Because of the unique electric properties of CPs and size effect, we next explored the electromagnetic absorption performances of these CPs nanostructures. A synergetic combination of electric loss and magnetic loss is used to explain the absorption mechanism of these CPs nano-structures.

Interactive method research of dual mode information coordination integration for astronaut gesture and eye movement signals based on hybrid model.

The lightweight human-robot interaction model with high real-time, high accuracy, and strong anti-interference capability can be better applied to future lunar surface exploration and construction work. Based on the feature information inputted from the monocular camera, the signal acquisition and processing fusion of the astronaut gesture and eye-movement modal interaction can be performed. Compared with the single mode, the human-robot interaction model of bimodal collaboration can achieve the issuance of complex interactive commands more efficiently. The optimization of the target detection model is executed by inserting attention into YOLOv4 and filtering image motion blur. The central coordinates of pupils are identified by the neural network to realize the human-robot interaction in the eye movement mode. The fusion between the astronaut gesture signal and eye movement signal is performed at the end of the collaborative model to achieve complex command interactions based on a lightweight model. The dataset used in the network training is enhanced and extended to simulate the realistic lunar space interaction environment. The human-robot interaction effects of complex commands in the single mode are compared with those of complex commands in the bimodal collaboration. The experimental results show that the concatenated interaction model of the astronaut gesture and eye movement signals can excavate the bimodal interaction signal better, discriminate the complex interaction commands more quickly, and has stronger signal anti-interference capability based on its stronger feature information mining ability. Compared with the command interaction realized by using the single gesture modal signal and the single eye movement modal signal, the interaction model of bimodal collaboration is shorter about 79% to 91% of the time under the single mode interaction. Regardless of the influence of any image interference item, the overall judgment accuracy of the proposed model can be maintained at about 83% to 97%. The effectiveness of the proposed method is verified.

Superior Enhancement of the UHMWPE Fiber/Epoxy Interface through the Combination of Plasma Treatment and Polypyrrole In-Situ Grown Fibers.

Obtaining a robust fiber/matrix interface is crucial for enhancing the mechanical performance of fiber-reinforced composites. This study addresses the issue by presenting a novel physical-chemical modification method to improve the interfacial property of an ultra-high molecular weight polyethylene (UHMWPE) fiber and epoxy resin. The UHMWPE fiber was successfully grafted with polypyrrole (PPy) for the first time after a plasma treatment in an atmosphere of mixed oxygen and nitrogen. The results demonstrated that the maximum value of the interfacial shear strength (IFSS) of the UHMWPE fiber/epoxy reached 15.75 MPa, which was significantly enhanced by 357% compared to the pristine UHMWPE fiber. Meanwhile, the tensile strength of the UHMWPE fiber was only slightly reduced by 7.3%, which was furtherly verified by the Weibull distribution analysis. The surface morphology and structure of the PPy in-situ grown UHMWPE fibers were studied using SEM, FTIR, and contact angle measurement. The results showed that the enhancement of the interfacial performance was attributed to the increased fiber surface roughness and in-situ grown groups, which improved the surface wettability between the UHMWPE fibers and epoxy resins.

ZnO-decorated SiC@C hybrids with strong electromagnetic absorption.

A novel strategy is provided to improve the absorption of SiC nanomaterials through surface carbonization of SiC nanowires and hydrolysis. SiC@C-ZnO composites were synthesized with different dosages of ZnNO3·6H2O. Composition, microstructure, and electromagnetic properties of the composites were characterized and analyzed. Results from TEM and XRD show that crystalline ZnO particles adhere to the surface of amorphous carbon, and the ZnO content increases as a function of a dosage of ZnNO3·6H2O. The as-prepared SiC@C-ZnO hybrids exhibit effective electromagnetic absorption, which is related to a synergy effect of different dielectric loss processes. The minimum reflection loss reached -65.4 dB at 11 GHz at a sample thickness of 3.1 mm, while the effective absorption bandwidth (EAB) reached 7 GHz at a sample thickness of 2.56 mm. Furthermore, the EAB of the samples can also cover the whole X band and Ku band at small sample thicknesses (2.09-3.47 mm). The excellent properties of the materials suggest great prospect as electromagnetic absorbers.

Controllable Fabrication of SiC@C-Fe3O4 Hybrids and Their Excellent Electromagnetic Absorption Properties.

In this work, a batch of novel ternary hybrids (SiC@C-Fe3O4), characterized by SiC nanowires core, carbon shell, and adhered Fe3O4 nanoparticles were controllably synthesized via surface carbonization of SiCnw followed by hydrothermal reaction. Carbon, which was derived from SiC with nanometer thickness, possesses an amorphous structure, while Fe3O4 nanoparticles are in a crystalline state. Simultaneously, the inducement of Fe3O4 nanoparticles can provide significant magnetic loss, which is well-tuned by changing the molar content of iron precursors (FeCl3·6H2O and FeCl2·4H2O). SiC@C-Fe3O4 hybrids show great electromagnetic absorption performance owing to the synergy effect of dielectric and magnetic losses. The minimum refection loss can reach to -63.71 dB at 11.20 GHz with a thickness of 3.10 mm, while the broad effective absorption bandwidth (EAB) can reach to 7.48 GHz in range of 10.52-18.00 GHz with a thickness of 2.63 mm. Moreover, the EAB can also cover the whole X band and Ku band. The outstanding performance of the obtained material implys that it is a promising candidate as an electromagnetic absorber.

C,N-codoped MoSi2 ceramic with excellent heat resistance for microwaves absorption application.

Microwave absorption (MA) materials with high heat resistance have a wide range of applications in many fields. In this work, a C,N-codoped MoSi2 ceramic was prepared via a facile solid-phase reaction method and its MA properties was investigated. On the one hand, the results indicate that this ceramic possesses excellent heat resistance and the weight of the MoSi2 is almost constant when the temperature is lower than 800°C. On the other hand, this ceramic shows good MA performance when the filler loading ratio increases to 30 vol%, the value of reflection loss (RL) could reach to -17.70 dB at 7.44 GHz with the thickness of 2.0 mm and the effective electromagnetic absorption bandwidth (RL below -10 dB) could reach to 1.88 GHz (9.28-11.16 GHz) with the thickness of 1.5 mm. Multi-polarization resonance loss is considered as the predominant attention mechanism on the MA performance of this MoSi2 ceramic. This research provides a new idea for understanding resonance mechanism and greatly expands the application scope of MoSi2 ceramic in MA area.

Oxidative stress response and proteomic analysis reveal the mechanisms of toxicity of imidazolium-based ionic liquids against Arabidopsis thaliana.

Ionic liquids (ILs) are extensively used in various fields, posing a potential threat in the ecosystem because of their high stability, excellent solubility, and biological toxicity. In this study, the toxicity mechanism of three ILs, 1-octyl-3-methylimidazolium chloride ([C8MIM]Cl), 1-decyl-3-methylimidazolium chloride ([C10MIM]Cl), and 1-dodecyl-3-methylimidazolium chloride ([C12MIM]Cl) on Arabidopsis thaliana were revealed. Reactive oxygen species (ROS) level increased with higher concentration and longer carbon chain length of ILs, which led to the increase of malondialdehyde (MDA) content and antioxidase activity, including superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX) and peroxidase (POD) activities. SOD, CAT, and GPX activities decreased in high ILs concentration due to the excessive ROS. Differentially expressed protein was analyzed based on Gene ontology (GO) and KEGG pathways analysis. 70, 45, 84 up-regulated proteins, and 72, 104, 79 down-regulated proteins were identified in [C8MIM]Cl, [C10MIM]Cl, and [C12MIM]Cl treatment, respectively (fold change ≥ 1.5 with ≥95% confidence). Cellular aldehyde metabolic process, mitochondrial and mitochondrial respiratory chains, glutathione transferase and oxidoreductase activity were enriched as up-regulated proteins as the defense mechanism of A. thaliana to resist external stresses. Chloroplast, photosynthetic membrane and thylakoid, structural constituent of ribosome, and transmembrane transport were enriched as the down-regulated protein. Compared with the control, 8 and 14 KEGG pathways were identified forup-regulated and down-regulated proteins, respectively, in three IL treatments. Metabolic pathways, carbon metabolism, biosynthesis of amino acids, porphyrin and chlorophyll metabolism were significantly down-regulated. The GO terms annotation demonstrated the oxidative stress response and effects on photosynthesis of A. thaliana in ILs treatment from biological process, cellular component, and molecular function categories.

The toxicity of ionic liquid 1-decylpyridinium bromide to the algae Scenedesmus obliquus: Growth inhibition, phototoxicity, and oxidative stress.

Although ionic liquids (ILs) are unlikely to act as air contaminants, their high solubility and slow degradation make them a potential threat to the aquatic environment. The IL 1-decylpyridinium bromide ([DPy]Br) is a common type of pyridine IL, which has varied applications such as in extraction, separation, and catalytic synthesis. Herein, the toxicity of [DPy]Br to S. obliquus is determined. Growth was inhibited by high-concentration [DPy]Br, whereas it had a hormetic effect at low concentrations. The IC50-96h was approximately 0.06mg/L. The cell membrane permeability of S. obliquus increased with [DPy]Br concentration, indicating that [DPy]Br can cause damage to the algae cell structure. Chlorophyll content decreased at high [DPy]Br concentration; chlorophyll fluorescence parameters, such as the maximum effective quantum yield of PSII (Fv/Fm), potential activity of PSII (Fv/F0), yield of the photochemical quantum [Y(II)], and the non-photochemical quenching coefficient (NPQ) were affected, suggesting that [DPy]Br can damage PSII. The ROS fluorescent images revealed that the morphology of cells changed gradually from fusiform to round. High ROS levels were observed with high concentrations of [DPy]Br, indicating that [DPy]Br induced oxidative stress on S. obliquus. The SOD and CAT activities increased when the concentration was lower than IC50, whereas they decreased when the concentration was higher than IC50. The relative ROS content was significantly correlated with growth inhibition rate, cell membrane permeability, chlorophyll content, and SOD and CAT activities. The increase of ROS content in algal cells is an important toxicological mechanism of [DPy]Br to S. obliquus.

Effect of ionic liquids with different cations and anions on photosystem and cell structure of Scenedesmus obliquus.

The rapid increase in the production and practical application of ionic liquids (ILs) could pose potential threats to aquatic systems. In this study, we investigated the effects of four ILs with different cations and anions, including 1-hexyl-3-methylimidazolium nitrate ([HMIM]NO3), 1-hexyl-3-methylimidazolium chloride ([HMIM]Cl), N-hexyl-3-metylpyridinium chloride ([HMPy]Cl), and N-hexyl-3-metylpyridinium bromide ([HMPy]Br), on photosystem and cellular structure of Scenedesmus obliquus. The results indicated that ILs are phytotoxic to S. obliquus. The contents of chlorophyll a, chlorophyll b and total chlorophyll decreased with increasing ILs concentrations. The chlorophyll fluorescence parameters of photosynthetic system II (PSII), including minimal fluorescence yield (F0), potential efficiency of PSII (Fv/Fo), maximum quantum efficiency of PSII photochemistry (Fv/Fm), yield of photochemical quantum [Y(II)], and non-photochemical quenching coefficient without measuring F0' (NPQ), were all affected. This indicates that ILs could damage PSII, inhibit the primary reaction of photosynthesis, interdict the process of electron-transfer and lead to loss of heat-dissipating ability. ILs also increased cell membrane permeability of S. obliquus, influenced the cellular ultrastructure, changed the morphology of algae cells and destroyed the cell wall, cell membrane and organelles. The results indicated that imidazolium ILs had greater effect than pyridinium ILs, NO3--IL and Br--IL had greater effect than Cl--IL. To minimize threats to the environment, the structure of ILs should be taken into consideration.

Effect of imidazolium-based ionic liquids with varying carbon chain lengths on Arabidopsis thaliana: Response of growth and photosynthetic fluorescence parameters.

As green and novel solvents, ionic liquids (ILs) are popular in many industries, which may threaten ecosystems. The effects of three imidazolium-based ILs with different alkyl chain lengths, including 1-octyl-3-methylimidazolium chloride ([C8mim]Cl), 1-decyl-3-methylimidazolium chloride ([C10mim]Cl), and 1-dodecyl-3-methylimidazolium chloride ([C12mim]Cl) on growth and photosystem of Arabidopsis thaliana were investigated. Root length, fresh weight, cell membrane permeability, and chlorophyll content of whole plant were significantly affected by ILs. Vein clearing, leaf chlorosis, and browning on the A. thaliana leaf abaxial surface occurred, with a dose-response relationship. The effect of ILs on whole plant increased with alkyl chain lengths. Chlorophyll fluorescence parameters of photosynthetic system II (PSII) were all affected in [C8mim]Cl and [C10mim]Cl treatments, electron-transfer was blocked, and photochemical energy conversion was damaged. There were no significant changes in chlorophyll fluorescence of newly-growing leaves in [C12mim]Cl treatment, but has severe effect on aged leaves. The number and size of starch granules and osmiophilic globules increased, plasmolysis and the chloroplast swelling occurred in [C8mim]Cl, [C10mim]Cl treatments and on aged leaves in [C12mim]Cl treatment, but no significant damages occurred on newly-growing leaves of [C12mim]Cl treatment, perhaps due to plant self-protection of plant. The results indicating the appropriate use of ILs is needed.

Controlled hydrothermal temperature provides tunable permittivity and an improved electromagnetic absorption performance of reduced graphene oxide.

Reduced graphene oxide (RGO) has been prepared by a hydrothermal reduction method to explore the effects of reaction temperature on its permittivity and electromagnetic absorption (EA) performance. This study shows that by controlling the oxygen functional groups on the RGO surface it is also possible to obtain an ideal EA performance without any other decorated nanomaterials.

Enantioselective oxidative stress and oxidative damage caused by Rac- and S-metolachlor to Scenedesmus obliquus.

The rational use and environmental security of chiral pesticides has gained the interest of many researchers. The enantioselective effects of Rac- and S-metolachlor on oxidative stress in Scenedesmus obliquus were determined in this study. Stronger green fluorescence was observed in response to S-metolachlor treatment than to Rac-metolachlor treatment, suggesting that more reactive oxygen species (ROS) were stimulated by S-metolachlor. ROS levels following S-metolachlor treatment were 1.92-, 8.31-, and 1.08-times higher than those observed following Rac-metolachlor treatment at 0.1, 0.2, and 0.3 mg/L, respectively. Superoxide dismutase (SOD) and catalase (CAT) were stimulated with increasing herbicide concentrations, with S-metolachlor exhibiting a greater effect. Oxidative damage in terms of chlorophyll (Chl) content, cellular membrane permeability, and cellular ultrastructures of S. obliquus were investigated. Chla and Chlb contents in algae treated with Rac-metolachlor were 2-6-fold higher than those in algae treated with S-metolachlor at 0.1, 0.2, and 0.3 mg/L. The cellular membrane permeability of algae exposed to 0.3 mg/L Rac- and S-metolachlor was 6.19- and 42.5-times that of the control. Correlation analysis implied that ROS are the major factor responsible for the oxidative damage caused by Rac- and S-metolachlor. Damage to the chloroplasts and cell membrane of S. obliquus, low production of starch granules, and an increased number of vacuoles were observed upon ultrastructural morphology analysis by transmission electron microscope. These results indicate that S-metolachlor has a greater effect on S. obliquus than Rac-metolachlor.

Enantioselective oxidative stress caused by chiral ionic liquids forms of 1-alkyl-3-methyl imidazolium tartrate on Scenedesmus obliquus.

Ionic liquids (ILs) are widely used, but their potential threat to the environment has recently gained more attention. The enantioselective oxidative stress caused by chiral ionic liquids (CILs), such as 1-alkyl-3-methyl imidazolium tartrate (RMIM T), on Scenedesmus obliquus was demonstrated in this study. Stronger green fluorescence was observed in response to l-(+)-RMIM T treatment than to d-(+)-RMIM T treatment, which suggested that more reactive oxygen species (ROS) were stimulated by l-(+)-RMIM T. Significantly higher ROS levels were recorded during the RMIM T treatments than in the control. There were 1.13-, 1.25-, 1.43-, 1.68-, and 1.96-fold increases over levels in the control in the 3, 5, 10, 15, and 25mg/L d-(-)-HMIM T treatments, respectively, and 1.26-, 1.37-, 1.58-, 1.86- and 2.08-fold increases over levels in the control in the 3, 5, 10, 15, and 25mg/L l-(+)-HMIM T treatments, respectively. The total soluble protein content decreased as the RMIM T concentration increased. The SOD and CAT activities were stimulated at lower concentrations, but were inhibited at higher concentrations. Regression analysis implied that ROS is the major factor responsible for the oxidative damage caused by RMIM T. The ultrastructural morphology analysis showed that plasmolysis and damage to the chloroplasts, starch granule decreases, and lipid granule increased, and pyrenoid and nucleoid damage had occurred. These results showed that enantioselective oxidative stress and oxidative damage were caused by d-(+)-RMIM T and l-(+)-RMIM T, and that l-(+)-RMIM T caused more damage than d-(+)-RMIM T.

Synthesis of hollow Cu1.8S nano-cubes for electromagnetic interference shielding.

The applications of inorganic semiconductor nano-structures as electromagnetic interference (EMI) shielding materials have been scarcely researched. Herein, we have designed hollow Cu1.8S nano-cubes via a mild anion exchange and etching process. These 30 wt% hollow Cu1.8S nano-cubes loaded in wax can display 30 dB of EMI shielding effectiveness (SE) in the whole tested frequency range of 2-18 GHz with a sample thickness of only 1 mm. This good EMI shielding performance can be attributed to the high electric conductivity, which leads to a high dielectric constant. This research opens up the possibility for the applications of inorganic semiconductor nano-structures as lightweight EMI shielding materials, especially in the areas of aerospace, automobile and sophisticated electronics.